GNRs - Page 5

Researchers at Rice University have shown that adding modified graphene nanoribbons to a polymer and then microwaving the mixture appears to reinforce wellbores drilled to extract oil and natural gas, which can make wells more stable and reduce production costs.

The team combined a small amount of the nanoribbons with an oil-based thermoset polymer. The combination then was cured in place with low-power microwaves emanating from the drill assembly, resulting in the composite plugging microscopic fractures. The combination allowed drilling fluid to seep through and destabilize the walls.

Researchers from Empa, the Max Planck Institute in Mainz and the Technical University of Dresden have succeeded, for the first time, in producing graphene nanoribbons (GNRs) with perfect zigzag edges from molecules. Electrons on these zigzag edges exhibit different (and coupled) rotational directions (referred to as "spin"). This could make GNRs highly attractive for next-gen electronics, namely spintronics.

In their work, the research team describes how it managed to synthesize GNRs with perfectly zigzagged edges using suitable carbon precursor molecules and a perfected manufacturing process. The zigzags followed a very specific geometry along the longitudinal axis of the ribbons. This is an important step, because researchers can thus give graphene ribbons different properties via the geometry of the ribbons and especially via the structure of their edges.

An international collaboration of scientists from the University of Basel and the Swiss Empa have studied the above-average lubricity of graphene using a two-pronged approach combining experimentation and computation. The researchers state that the results of this study help them to better understand the manipulation of chemicals at the nano level and pave the way for creating frictionless coatings.

To do this, they anchored 2D strips of carbon atoms (graphene nanoribbons) to a sharp tip and dragged them across a gold surface. Computer-based calculations were used to investigate the interactions between the surfaces as they moved across one another. Using this approach, the research team hoped to gain a better understanding of the causes of superlubricity.

Researchers at Rice University have created a thin coating of graphene nanoribbons in epoxy, that has proven effective at melting ice on a helicopter blade. This coating may be an effective real-time de-icing mechanism for aircraft, wind turbines, transmission lines and other surfaces exposed to cold weather. In addition, the coating may also help protect aircraft from lightning strikes and provide an extra layer of electromagnetic shielding.

The scientists performed tests in which they melted centimeter-thick ice from a static helicopter rotor blade in a -4 degree Fahrenheit environment. When a small voltage was applied, the coating delivered electrothermal heat - called Joule heating - to the surface, which melted the ice.

Researchers at the National Institute of Standards and Technology (NIST) have simulated a new concept for rapid, accurate gene sequencing by pulling a DNA molecule through a tiny hole in graphene and detecting changes in electrical current. This new method might ultimately be faster and cheaper than conventional DNA sequencing.

The study suggests that the method could identify about 66 billion bases (the smallest units of genetic information) per second with 90% accuracy and no false positives. Conventional sequencing involves separating, copying, labeling and reassembling pieces of DNA to read the genetic information. The new NIST way offers a twist on the more recent "nanopore sequencing" idea of pulling DNA through a hole in specific materials, originally a protein. This concept is based on the passage of electrically charged particles (ions) through the pore and poses challenges such as unwanted electrical noise and inadequate selectivity.

An international team of researchers at Tohoku University in Japan has demonstrated the ability to interconnect graphene nanoribbons (GNRs) end to end, using molecular assembly that forms elbow structures (interconnection points). This development may provide the key to unlocking GNRs’ potential in high-performance and low-power-consumption electronics.

GNRs are interesting as their width determines their electronic properties; Narrow ones are semiconductors, while wider ones act as conductors, which basically  provides a simple way to engineer a band gap into graphene for use in electronics.

Researchers at Aalto University in Finland have successfully realized extremely thin metallic graphene nanoribbons (GNRs) - only 5 carbon atoms wide. The team demonstrated fabrication of the GNRs and measured their electronic structure, with results that suggest that these extremely narrow ribbons could be used as metallic interconnects in future microprocessors.

GNRs have been suggested as ideal wires for use in future nanoelectronics: when the size of the wire is reduced to the atomic scale, graphene is expected to outperform copper in terms of conductance and resistance to electromigration - the typical breakdown mechanism in thin metallic wires. However, previously demonstrated graphene nanoribbons have been semiconducting, which hampers their use as interconnects. Now, the researchers have shown that certain atomically precise graphene nanoribbon widths are nearly metallic, in accordance with earlier predictions based on theoretical calculations.

A team of international scientists, led by the University of Exeter and carried out as part of an EU project, have engineered a fascinating hybrid structure, or metamaterial, that possesses specific characteristics that are not found in natural materials.

The collaborative team combined nanoribbons of graphene, in which electrons are able to oscillate backwards and forwards, together with a type of antenna called a split ring resonator. A specific design combining these two elements lead to a system which strongly interacts with electromagnetic radiation, according to the researchers. In these experiments, the team used light with very long wavelengths, far beyond what the human eye can see, to show that these new structures can be used as a type of optical switch to interrupt, and turn on and off, a beam of this light very quickly.

Researchers from the University of Illinois at Urbana-Champaign (UIUC) have developed a new nanopore sequencing method based on graphene nanoribbons that detects double and single stranded DNA in different configurations. This graphene-based detector shows great sensitivity and holds promise for developing a portable, high-throughput sequencer that can also detect DNA morphological transformations.

In a nanopore sequencing reaction, DNA passes through a nanopore drilled in a membrane to which an electrical voltage is applied. When DNA goes through the pore, it causes dips in the electrical current. Reading the magnitude and duration of the electrical changes allows to identify the bases that go through.

Swansea University researchers, along with Haydale, examined the feasibility of using carbon materials as catalysts for dye sensitized solar cells (DSCs), a potentially low-cost alternative to silicon-based solar cells.

Haydale HDPlas low pressure cold plasma technology was used to introduce functional groups onto graphene. This is a process known to improve the material’s performance as a counter electrode in DSCs as it improves the dispersion of carbon nanomaterials without the need for surfactants and decreases the density of the powder without increasing the SSA (Specific Surface Area a useful way to quantify nanostructure and estimate catalytic activity).